In conventional sensing and electronic drive circuitry for connection to and operation with the read/write heads of magnetic disk drives, the magnetic core of the head is magnetically coupled to and insulated from a winding which in turn is connected to an amplifier. The amplifier is adapted to either amplify read signals taken from a magnetic disk or to amplify write signals applied to the read/write head of the disk drive. The winding is typically insulated from the other elements of the read/write head by a polymer, such as a photoresist, which will have a resistance typically on the order of 1000 Megohms. As is well known, the read/write head is positioned closely adjacent to the surface of the magnetic disk surface, and these closely spaced devices form two plates of a parasitic capacitance. This parasitic capacitance may thus be charged with a current drawn through the resistance of the above insulating material located between the winding and the other elements of the read/write head.
The problem caused by the above parasitic RC circuit is that the charged parasitic capacitance will frequently discharge during a read operation of the disk drive and thereby produce an error in the read data. This discharge takes place in either one of two modes. In one mode, the discharge takes place randomly over the surface of the disk, in which case it has been referred to as an "electrical storm". In the other mode, the discharge will take place repeatedly at a surface irregularity on the disk every time the irregularity passes underneath the read/write head. The latter mode has been referred to as the "Hilton effect".
Prior efforts have been made to solve this problem and they involve reducing the DC bias applied to the above described amplifier in order to reduce the DC voltage across the head-to-disk surface parasitic capacitance. However, this approach has not proven satisfactory because of the DC biasing levels required for normal and acceptable amplifier operation with magnetic disk drives where only positive voltage supplies are available.